This invention relates to methods and complexes for forming metal-containing films, such as metal or metal alloy films, on substrates, particularly during the manufacture of semiconductor device structures. The complexes include a Group IVB, VB, or VIB metal and are particularly suitable for use in a chemical vapor deposition system.
As device geometries shrink it is becoming increasingly important to look at alternatives for titanium as a contact/barrier material. For example, as contact holes or vias (i.e., very small openings located, for example, between surface conductive paths and or xe2x80x9cwiringxe2x80x9d and active devices on underlying layers) become narrower and deeper, they are harder to fill with metal. Also, metalorganic sources for titanium nitride, for example, which is used as a metallization barrier, are particularly difficult to find that have sufficiently low and stable resistance to be suitable for very small contacts. Furthermore, it is difficult to deposit pure titanium by chemical vapor deposition at low temperatures because currently available precursors require high temperatures to remove halogen from films deposited from titanium halides or are contaminated with carbon when common metalorganic precursors are used.
Thus, there is a continuing need for methods and precursor compositions for the deposition of titanium and metals that are suitable replacements for titanium in metal-containing films, on substrates such as those used in semiconductor structures, particularly using vapor deposition processes.
The present invention provides methods for forming metal-containing films, particularly Group IVB, VB, and VIB metal-containing films on substrates, such as semiconductor substrates or substrate assemblies during the manufacture of semiconductor structures. Group IVB (i.e., Group 4) includes Ti, Zr, and Hf. Group VB (i.e., Group 5) includes V, Nb, and Ta. Group VIB (i.e., Group 6) includes Cr, Mo, and W. The methods involve forming a metal-containing film using a Group IVB, VB, or VIB metal complex, preferably a Group VB metal complex. The metal-containing film can be used in various metallization layers, particularly in multilevel interconnects, in integrated circuit structures.
The metal-containing film can be a single Group IVB, VB, or VIB metal, or a metal alloy containing a mixture of such metals or one or more metals from these groups and one or more metals or metalloids from other groups in the Periodic Chart, such as Si, Ge, Sn, Pb, Bi, etc. Furthermore, for certain preferred embodiments, the metal-containing film can be a nitride, phosphide, arsenide, stibnide, sulfide, selenide, telluride, or combinations thereof.
Thus, in the context of the present invention, the term xe2x80x9cGroup IVB-VIB metal-containing filmxe2x80x9d or simply xe2x80x9cmetal-containing filmxe2x80x9d includes, for example, relatively pure films of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, or tungsten. The term also includes alloys of such metals with or without other metals or metalloids, as well as complexes of these metals and alloys with other elements (e.g., N, P, As, Sb, S, Se, and Te), or mixtures thereof. The terms xe2x80x9csingle Group IVB-VIB metal filmxe2x80x9d or xe2x80x9cGroup IVB-VIB metal filmxe2x80x9d refer to relatively pure films of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, or tungsten. The term xe2x80x9cmetal alloy filmxe2x80x9d refers to films containing titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten in various combinations with each other or with other metals or metalloids. That is, if there are no metals or metalloids from groups in the Periodic Chart other than those from Groups IVB, VB, or VIB, the alloy films contain combinations of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten.
One preferred method of the present invention involves forming a film on a substrate, such as a semiconductor substrate or substrate assembly during the manufacture of a semiconductor structure, by providing a substrate (preferably, a semiconductor substrate or substrate assembly), and providing a precursor composition comprising one or more complexes of the formula:
[(R1)NC(R2)C(R3)N(R4)]xMLyxe2x80x83xe2x80x83(Formula I)
wherein: M is a Group IVB, VB, or VIB metal; each R1, R2, R3, and R4 group is independently H or an organic group; L is selected from the group of CO, NO, CN, CS, CNR5, R6CN, or R7, wherein each R5, R6, and R7 group is independently an organic group; x=1 to 4; and y=1 to 4; and forming a metal-containing film from the precursor composition on a surface of the substrate (preferably, a semiconductor substrate or substrate assembly). Using such methods the complexes of Formula I are converted in some manner (e.g., thermally decomposed) and deposited on a surface to form a metal-containing film. Thus, the film is not a film of the complex of Formula I, but may contain only the Group IVB, VB, or VIB metal, M, or metal alloys, for example.
As used herein, Formula I is an empirical formula. That is, it expresses in simplest form the relative number of atoms in a molecule. Thus, the compounds of Formula I can be monomers, dimers, trimers, etc. Typically, however, they are monomers and Formula I is the actual molecular formula. Such complexes are typically referred to as xe2x80x9cdiazadienexe2x80x9d or xe2x80x9cdiazabutadienexe2x80x9d complexes.
Complexes of Formula I are neutral complexes and may be liquids or solids at room temperature. If they are solids, they are preferably sufficiently soluble in an organic solvent or have melting points below their decomposition temperatures such that they can be used in flash vaporization, bubbling, microdroplet formation techniques, etc. However, they may also be sufficiently volatile that they can be vaporized or sublimed from the solid state using known chemical vapor deposition techniques. Thus, the precursor compositions of the present invention can be in solid or liquid form. As used herein, xe2x80x9cliquidxe2x80x9d refers to a solution or a neat liquid (a liquid at room temperature or a solid at room temperature that melts at an elevated temperature). As used herein, a xe2x80x9csolutionxe2x80x9d does not require complete solubility of the solid; rather, the solution may have some undissolved material, preferably, however, there is a sufficient amount of the material that can be carried by the organic solvent into the vapor phase for chemical vapor deposition processing. Thus, a vaporized presursor composition includes vaporized molecules of precursor complexes of Formula I either alone or optionally with vaporized molecules of other compounds in the precursor composition, including solvent molecules, if used.
Preferred embodiments of the methods of the present invention involve the use of one or more chemical vapor deposition techniques, although this is not necessarily required. That is, for certain embodiments, sputtering, spin-on coating, etc., can be used.
Methods of the present invention are particularly well suited for forming films on a surface of a semiconductor substrate or substrate assembly, such as a silicon wafer, with or without layers or structures formed thereon, used in forming integrated circuits. It is to be understood that methods of the present invention are not limited to deposition on silicon wafers; rather, other types of wafers (e.g., gallium arsenide wafer, etc.) can be used as well. Also, methods of the present invention can be used in silicon-on-insulator technology. Furthermore, substrates other than semiconductor substrates or substrate assemblies, can be used in methods of the present invention. These include, for example, fibers, wires, etc. If the substrate is a semiconductor substrate or substrate assembly, the films can be formed directly on the lowest semiconductor surface of the substrate, or they can be formed on any of a variety of the layers (i.e., surfaces) as in a patterned wafer, for example. Thus, the term xe2x80x9csemiconductor substratexe2x80x9d refers to the base semiconductor layer, e.g., the lowest layer of silicon material in a wafer or a silicon layer deposited on another material such as silicon-on-sapphire. The term xe2x80x9csemiconductor substrate assemblyxe2x80x9d refers to the semiconductor substrate having one or more layers or structures formed thereon.
A chemical vapor deposition system is also provided. The system includes a deposition chamber having a substrate positioned therein; a vessel containing a precursor composition comprising one or more complexes of Formula I; and a source of an inert carrier gas for transferring the precursor composition to the chemical vapor deposition chamber.